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Protected Areas (PAs) are important spaces for the protection of biodiversity, capable of halting deforestation and collaborating in the intentions to reduce climate change. The objective of this work is to demonstrate the importance of Protected Areas in the state of Mato Grosso in the avoided deforestation and to estimate their contribution to the reduction of greenhouse gas emissions and soil erosion. The methodology was based on secondary data and the use of a GIS environment. As a result, it was found that in Mato Grosso there are 120 PAs between federal, state and municipal, they protect 6% of the territorial area of the state and most are located in the Amazon biome. Mato Grosso's Forest cover in 2019 was 49.8 million hectares, with an estimated forest carbon stock of over 16.4 GtCO2. The PAs were created over the years in the state, but the greatest number occurred between 2000 and 2005 and together, in 2019 they were responsible for preventing the deforestation of more than 726,000 hectares of forest, 10 million tons of erosion and storing 281 million tons of carbon, which if traded on the credit market would have an estimated value of more than US$1.25 million. If the PAs did not exist and if deforestation were to be carried out, the cost of replacing this area would be more than US$2.73 billion. Therefore, the importance of PAs in environmental conservation and in the economy related to forest cover is notorious. [ABSTRACT FROM AUTHOR]

Bananas are a worldwide cultivated crop and one of the main agricultural activities in Brazil. The banana orchards cultivated in the region of São Paulo State are under native areas of the Atlantic Forest biome. The Atlantic Forest has suffered agricultural and urban pressure for many years. Banana crops require soil management and superficial vegetation removal in the first cycles. We conducted a study aiming to understand the impact of long-standing banana cultivation in the Atlantic forest region. Soil samples in banana plantations (EBP) and forest remnants (FR) were collected from trenches with 0- to 100-cm layers. The soil bulk density in EBP until 30-cm depth was 12.76% higher than that in FR. Quantifications of macropores and micropores in FR reached values higher than those in EBP. The results showed that carbon stocks decreased from the top to the deeper layers. Thirty years after the conversion, the FR treatment accumulated 28.23% more carbon than EBP. Considering our results, it was evident that changes in physical and chemical properties reflected the negative impacts of the banana plantations, cropped through conventional management, when converted from forest even in regard to a remnant one. These findings, showed for the first time, lead us to understand the soil management of banana plantations, following conventional agriculture systems, as a potential carbon stock reducer and a factor resulting in the loss of soil quality in the region. Additionally, our data can be used by environmentalists and government policymakers to promote environmental sustainability. [ABSTRACT FROM AUTHOR]

The need to put into practice sustainable agricultural production systems has been supported by agroecology science that seeks to optimize land use to food production with the lowest impact on soil. This study evaluated soil quality, based on physical and chemical attributes, in agroforestry (AGF) and silvopastoral (SILVP) systems developed for large-scale food production. The study was carried out in the municipality of Itirapina, state of São Paulo, in two areas with AGF and SILVP system, compared to an area with a forest fragment and another with pasture in a Quartzipisamment Sand Neosol. The soil collections were carried out in the layers of 0.00–0.05, 0.05–0.10, 0.10–0.20, and 0.20–0.40 m, where physical soil attributes were evaluated (total porosity, microporosity, and microporosity, density, mean diameter of aggregates) as well as chemical attributes (macro- and micronutrients), in addition to carbon and nitrogen storage. To interpret the data, Tukey's test was applied to compare means, and principal component analysis was used to better characterize the study environments. The results showed that agroforestry and silvopastoral systems developed for large-scale production are efficient in improving chemical and physical attributes that reflect on soil quality, especially in the superficial layers of the soil, overcoming pasture and the natural regeneration process. Carbon and nitrogen storage were the main variables that differentiated the production systems, highlighting the importance of the AGF and SILVP systems as more sustainable agricultural intensification strategies, even in soils of low agricultural suitability. [ABSTRACT FROM AUTHOR]

No-till (NT) contributes to improving soil quality. This study aimed to quantify the organic carbon (C) content of light SOM fractions at sites under pasture, native forest, or NT for different periods and assess the influence of management systems on C and nitrogen (N) stocks and C/N ratio in a Ferralsol in Paraná State, Brazil. Soil samples were collected from the 0–5, 5–10, 10–20, 20–30, 30–40, 40–50, and 50–60 cm layers at sites managed under NT for 6, 14, or 22 years (NT6, NT14, and NT22, respectively); a site under NT management for 12 years, followed by 4 years of Brachiaria intercropping (NT12 + B); a permanent pasture (PP); and a native forest (NF) site. A density fractionation was carried in 0–5 and 5–10 cm layers and then were obtained the organic C contents in fLF (fLF-C) and oLF (oLF-C). The stocks of fLF-C, oLF-C and total C stocks in the light fraction were then calculated. It was also determined the natural abundance of 13C and 15N and the contents of C and N were used to calculate the C/N ratio of each layer. Management systems promoted changes in C dynamics in light SOM fractions, δ13C, δ15N, and C/N ratio. Differences in 13C isotopic composition were observed only at depths greater than 30 cm, with the NF site differing from the others (− 25‰ δ13C). For NT6, NT14, NT22, NT12 + B, and NF, δ15N values indicated isotopic enrichment with depth. At the PP site, there was a decrease in isotopic enrichment with depth, ranging from just over 12‰ δ15N in topsoil to 10‰ δ15N in the 60 cm layer. Multivariate analyses were used to group sites according to the analyzed variables. In the 0–5 cm layer, PP soil was associated with 15N isotopic composition, whereas NT6, NT14, NT22, and NT12 + B had a strong correlation with C/N ratio. NF showed a strong association with C contents and stocks in light fractions. In the 5–10 cm layer, PP had a strong correlation with δ13C and C/N ratio. For NF soil, there was a correlation with light fraction C stock, free light fraction C content and stock, and δ15N isotopic composition. In contrast to the other management systems, NT12 + B was strongly correlated with occluded light fraction C content and stock in the 5–10 cm layer. These results underscore the importance of evaluating labile SOM fractions when assessing the quality of anthropized environments and how management practices adopted over time can affect the SOM light fraction dynamics. The introduction of other crops, such as Brachiaria, during the production cycle becomes a solution for increasing C stocks in cultivated soils. [ABSTRACT FROM AUTHOR]

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• The soil carbon stock is enhanced by the Oxisol's characteristics. • Litterfall and throughfall drive the spatial variability of carbon stocks in shallow layers. • Temporal dynamics of soil moisture improve carbon mineralization in deep layers. • Unprecedently high carbon stock in deep layers highlights the potential for mitigating climate change. There is a significant gap in the literature concerning the potential of tropical soils to stock carbon in the Brazilian Atlantic Forest biome. Furthermore, the key drivers responsible for the variability in carbon storage in tropical soils remain unknown. Therefore, experimental studies are crucial to highlight the importance of Atlantic Forests in storing organic matter, considering that forest soils are one of the most important carbon reservoirs on Earth. This study aimed: (i) to determine soil carbon stocks at the depths of 0–5 cm, 5–10 cm, 10–20 cm, 20–30 cm, 30–40 cm, 40–60 cm, and 60–100 cm in a forest fragment located in the Atlantic Forest hotspot; (ii) to describe the temporal variability of soil carbon stocks; and (iii) to identify the main biotic and abiotic drivers that influence their temporal and spatial variations. Soil carbon stocks at a 1-meter depth ranged from 201 to 396 Mg C/ha, with a spatial variability of 22.3 %. The highest accumulation of soil carbon in the 1-meter depth was in December (290.8 Mg C/ha), while the lowest was in August (246.1 Mg C/ha), highlighting the soil carbon stocks' seasonality in the Atlantic Forest. Concerning the vertical distribution, ∼50 % of the soil carbon stocks were found in the 0–30 cm layer. The main drivers of carbon spatial distribution varied across different soil layers: (i) litterfall and long-term spatiotemporal patterns of throughfall were the primary drivers in the shallower layers (0–5 cm and 5–10 cm), while (ii) variability in tree sizes and long-term temporal dynamics of soil moisture were the main drivers in the deeper layers. Oxisols' characteristics were crucial for the unprecedently high carbon stocks observed in the deep layers (67.7 Mg C/ha). Thus, the Atlantic Forest-Oxisol association is a prominent strategy to improve carbon stocks in Brazilian tropical soils. [ABSTRACT FROM AUTHOR]

[Display omitted] • Prescribed fire (PF) is a land management practice. • Knowledge on PF application in Brazilian mountain environments is scarce. • Soil properties and organic matter chemistry were monitored in the short and medium term after PF application. • Organic matter recovered to its initial condition after 240 days since PF. Prescribed fire (PF) is a management practice used ecosystems where the occurrence of wildfires is high due to the accumulation of biomass on the surface. In general, studies dealing with fire-affected soils evidence the degradation of less thermo-labile structures, with the preservation of more thermo-stable phases. As studies in mountain environments in Brazil are scarce and considering that the practice of PF has been on the rise in recent years, the present study aimed to quantifying and characterizing the impact of PF on soil organic matter in the Itatiaia National Park, Rio de Janeiro-Brazil. In a 240 days period, we assessed the impact of PF on soil pH, base cations release, available P, C and N contents and stocks, soil organic matter (SOM) quality. Among other techniques, we applied ATR-FTIR and 13 C NMR spectroscopy. Soil chemical and physical attributes were also quantified. At 10 days, PF application caused the release of labile organic carbon (LOC) forms, inducing an increase in content of humic fractions in the form of C-FA and C-HA. The humification process, nevertheless, occurred at a lower speed than the incorporation of LOC. Humin contents, in fact, did not systematically increase with time. At 10 days following PF, a decrease in carbohydrates and peptides occurred, with greater HA aromaticity. After 240 days since PF, the structural characteristics of HA were restored to levels like the original (pre-PF) condition. At 120 days after PF, the pH value, base saturation, Mg, Na and P increased in soil. However, the amount of C and N accumulated in the soil did not increase with PF application. We observed that up to 120 days of PF, the mineralization process seems to occur in priority over humification. A period longer than 240 days seems anyway needed to restore soil C and N stocks. [ABSTRACT FROM AUTHOR]

Farming sugarcane, as a renewable source of ethanol for use as a fuel, is a common practice in Brazilian agriculture. Despite being renewable, whether ethanol use actually reduces greenhouse gas (GHG) emissions depends on how the sugarcane is produced. Studies have shown that land use changes due to sugarcane farming are responsible for a substantial amount of the carbon emitted into the atmosphere, and may be equivalent to, or even greater than, the great “villains” of global warming–the fossil fuels. In the context of climate change, are there alternative land use changes that could create a lower overall carbon debt for ethanol and sugarcane production? In attempting to answer this question, this study aimed to: (i) map carbon stocks in the Brazilian biomes; (ii) quantify the carbon loss under different scenarios of land use changes for sugarcane-ethanol production; (iii) calculate the payback time for land conversion to sugarcane; and (iv) quantify the current areas of cultivated and degraded pasture by biome. The results show that the carbon debt from the deforestation of Brazilian biomes for ethanol production is equivalent to 608 Mg CO 2  ha −1 for the Amazon, 142 Mg CO 2  ha −1 for the Cerrado and 212 Mg CO 2  ha −1 for the Atlantic Forest with respective payback times of 62, 15 and 22 years. However, carbon emitted from the conversion of existing pasture land to sugarcane production rather than forest would be much smaller, with a shorter payback time. We conclude that pasturelands, especially those already degraded, would be the most suitable areas for land conversion to sugarcane production for ethanol. Pasture recovery would increase carbon stocks, reduce GHG emissions and reduce the negative direct and indirect land use changes associated with sugarcane expansion in Brazil. [ABSTRACT FROM AUTHOR]

• Desertification is a major environmental problem in arid and semiarid regions. • We evaluated the influence of vegetation cover and rainfall on erosion. • Vegetation cover significantly influenced the total soil carbon and nitrogen stocks. • Rainfall intensity significantly influenced the runoff rate. • The results of this study can be used as a reference for calibrating erosion models. Desertification is a major environmental problem in arid, semiarid, and dry sub-humid regions throughout the world, which causes considerable reductions of ecosystem services, increased food insecurity, and poverty. The influence of vegetation cover and rainfall intensity on the dynamics of water infiltration, surface runoff, and soil loss was measured in situ in a desertification zone in the semi-arid region of Brazil. Twenty-four plots were evaluated in two areas, each with the same type of soil that is predominant in the region: 1) Luvisol with dense vegetation cover (LD) and 2) Luvisol with sparse vegetation cover (LS). A rainfall simulator was used to simulate either 60 or 100 mm h−1 of rainfall. Soil hydraulic conductivity, soil water retention curves, and soil carbon and nitrogen stocks were also determined. Water infiltration was greater in the LD (53 mm h−1) than in the LS (15 mm h−1), while the runoff rates were 27 mm h−1 for the LD and 61 mm h−1 for the LS. Rainfall intensity significantly influenced the time when runoff started and the runoff rate accelerated soil loss. Vegetation cover significantly influenced the total soil carbon and nitrogen stocks, as well as the saturated hydraulic conductivity of the soil. This is the first study in a semi-arid desertification zone of Brazil that used simulated rainfall to determine effects rain intensity on soil properties. The results of this study can be used as a reference for calibrating erosion models in areas undergoing a desertification process. [ABSTRACT FROM AUTHOR]

There is increasing demand for agricultural commodities that are produced in a climate-friendly manner. At the same time, in many or most tropical countries there is need for intensification of agricultural production to increase yields and incomes, and this usually requires higher external inputs that may cause additional greenhouse gas emissions. Here we investigate if production methods that have a beneficial effect on the climate (are climate-friendly) are compatible with increased inputs and yields for traditional, shaded cocoa ( Theobroma cacao) production systems (locally known as cabrucas) in southern Bahia, Brazil. We use two easily measurable and manageable dimensions of climate friendliness, namely the carbon (C) stocks in the large trees and the C footprint as related to on-farm agrochemical and fuel use. Through interviews and field inventories in 26 cabruca farms representing a range of production practices and intensities, we identify the combinations of management practices, yields, C stocks and C footprints typically found in the region. We find that yield levels up to the highest encountered yield of 585 kg ha, or twice the current regional average of 285 kg ha, are compatible with an aboveground C stock in the large shade trees (>30 cm diameter at breast height) of up to 65 Mg ha and up to 55 % shade. Higher C stocks and shade levels are generally associated with yields below the regional average. Input-related C emissions increased non-linearly with increasing yield, but even the highest encountered yields were compatible with low (<0.25 kg COe kg of cocoa) to medium (<0.5 kg COe kg of cocoa) input-related emission levels. Cocoa yields responded positively to increased fertilizer applications, provided that other factors, including shade levels, were not limiting. Consequently, the highest input-related emissions (>1 kg COe kg of cocoa) were related to large fertilizer applications that did not proportionately increase yields. We conclude that doubling the cocoa output from southern Bahia, where cabrucas are the predominant form of growing cocoa, is compatible with climate-friendly production practices, measured by local standards. We suggest that the presented methodology can be used to identify opportunities for climate-friendly intensification of tree crops more generally, thereby increasing the contribution of commodity production to global climate change mitigation. [ABSTRACT FROM AUTHOR]

Deforestation for urbanization and agriculture expansion drastically reduced the area of the Atlantic forest biome in Brazil. To reverse this process, rehabilitating degraded lands, restoration plantations with native tree species show significant potential to rebuild the forest habitat and promoting carbon sequestration. High input silviculture (intensive fertilization and weed control), similar to those applied in commercial production forest plantations can increase productivity, accelerating forest restoration process. We evaluated the effects of two contrasting silvicultural systems, “traditional” (based on common silviculture of forest reforestation in Brazil – low input) and “intensive” (based on commercial plantations – high input) on carbon (C) stocks of a restoration plantation. We also compared the plantations with a mature forest remnant. Six years after planting, forest C stock (coarse roots and aboveground biomass) under intensive silviculture reached 23.3 Mg C ha −1 , more than 3-fold the stock under traditional silviculture (6.9 Mg C ha −1 ). Under both silvicultural systems, soil showed constant C stock (average of 33 Mg C ha −1 ). The C accumulation in biomass with intensive silviculture reached 12.8% of that stored in the mature forest (181.5 Mg C ha −1 ), compared with just 3.8% for traditional silviculture. Intensive silviculture provided nutrients and reduced competition with weeds, increasing growth and carbon sequestration. Forest plantations aiming at restoration and also carbon sequestration are practicable, and are highly responsive to intensive silviculture. [ABSTRACT FROM AUTHOR]

A variety of environmental and biotic factors determine vegetation growth and affect plant biomass accumulation. From temperature to species composition, aboveground biomass storage in forest ecosystems is influenced by a number of variables and usually presents a high spatial variability. With this focus, the aim of the study was to evaluate the variables affecting live aboveground forest biomass (AGB) in Subtropical Moist Forests of Southern Brazil, and to analyze the spatial distribution of biomass estimates. Data from a forest inventory performed in the State of Rio Grande do Sul, Southern Brazil, was used in the present study. Thirty-eight 1-ha plots were sampled and all trees with DBH ≥9.5cm were included for biomass estimation. Values for aboveground biomass were obtained using published allometric equations. Environmental and biotic variables (elevation, rainfall, temperature, soils, stem density and species diversity) were obtained from the literature or calculated from the dataset. For the total dataset, mean AGB was 195.2Mg/ha. Estimates differed between Broadleaf and Mixed Coniferous-Broadleaf forests: mean AGB was lower in Broadleaf Forests (AGBBF=118.9Mg/ha) when compared to Mixed Forests (AGBMF=250.3Mg/ha). There was a high spatial and local variability in our dataset, even within forest types. This condition is normal in tropical forests and is usually attributed to the presence of large trees. The explanatory multiple regressions were influenced mainly by eleva- tion and explained 50.7% of the variation in AGB. Stem density, diversity and organic matter also influenced biomass variation. The results from our study showed a positive relationship between aboveground biomass and elevation. Therefore, higher values of AGB are located at higher elevations and subjected to cooler temperatures and wetter climate. There seems to be an important contribution of the coniferous species Araucaria angustifo- lia in Mixed Forest plots, as it presented significantly higher biomass than angiosperm species. In Brazil, this endangered species is part of a high diversity forest (Araucaria Forest) and has the potential for biomass storage. The results of the present study show the spatial and local variability in aboveground biomass in subtropical forests and highlight the importance of these ecosystems in global carbon stock, stimulating the improvement of future biomass estimates. [ABSTRACT FROM AUTHOR]

Questions Grasslands are usually neglected as potential carbon stocks, partially due to the lack of studies on biomass and carbon dynamics in tropical grasslands. What is the importance of Brazilian tropical wet grasslands as carbon sinks? Does fire frequency and season affect biomass and carbon allocation in Brazilian wet grasslands? Location Wet grasslands, tropical savanna, Jalapão, Tocantins, northern Brazil. Methods We determined biomass above- and below-ground, estimated carbon stocks in biennially burned plots ( B2) and plots excluded from fire for 4 yr ( B4). Moreover, we determined biomass in both rainy and dry seasons. Samples were 0.25 m × 0.25 m × 0.2 m (eight samples per treatment, applying a nested design, total of 48 samples). The biomass was classified in above-ground graminoids, forbs and dead matter, and below-ground roots and other below-ground organs. We used ANOVA to compare variables between treatments and seasons. Results More than 40% of the total biomass and carbon stocks were located below-ground, mostly in roots. A high proportion of dead biomass ( B4) was found in the above-ground material, probably due to low decomposition rates and consequent accumulation over the years. Although these grasslands do not experience water stress, we found significant evidence of resource re-allocation from below-ground organs to the above-ground biomass in the rainy season. Conclusions We found more dead biomass in the rainy season, probably due to low decomposition rates, which can increase fire risk in these grasslands during the following dry season. These tropical wet grasslands stored high amounts of carbon (621 to 716 g C.m−2), mostly in the roots. Thus, policymakers should consider tropical grasslands as potential carbon stocks, since they are one of the most threatened and unprotected ecosystems in Brazil. [ABSTRACT FROM AUTHOR]

Abstract: Termites play an important role in the carbon cycling of several ecosystems. Part of this C is directed to the formation of nests or mounds, but few published estimations have been made of the proportions of this C in relation to those in the vegetation and/or in the litter. The dynamics of C of Constrictotermes cyphergaster nests, in the driest part of caatinga, in semiarid northeast Brazil, was calculated considering all present, formed and abandoned nests in 1ha, for two years. Carbon concentrations were determined from samples taken from the core and the external layer of nests. Total aboveground biomasses of trees and shrubs in the 1ha were estimated by allometric equations. C concentrations were lower in the external layer (24–33gkg−1) than in the nest cores (38–76gkg−1). The stock of C in the nests of the sampled ha was 61.5kg, which represents about 0.6% of that in the plant aboveground biomass (10.25MgCha−1). The C in the annual formation and abandonment of nests (10.2kgha−1 year−1) corresponded to 16% of the stock of C in the nests, 1.1% of the carbon in the annual litter production (925kgCha−1 year−1) and 3.1% of the non-leaf litter. Although lower than the few values reported for more humid areas, these proportions indicate that C. cyphergaster nest formation contributes to C cycling in this very dry semiarid caatinga site. [ABSTRACT FROM AUTHOR]

Drought events may induce mangrove mortality and dieback events worldwide as a result of climate extremes. As mangroves sequester large quantities of carbon, quantifying the losses of these stocks following climate disturbances may guide wetland governance strategies globally. In Southeast Brazil, we determined the total ecosystem carbon stocks (TECS) of pristine mangroves that were up to 1851 Mg of carbon per hectare (Mg C ha−1), which are the highest stocks measured from South American and raising estimates of Brazil's mangrove TECS to 0.52 Pg C. A mangrove mortality event in the same estuary resulted in a 14.6 % decrease in TECS (270.5 Mg C ha−1) and loss of 20 % of mangrove soil carbon within less than 2-years. Carbon dioxide emissions from this impact were 992.8 Mg CO 2 e ha−1, which are slightly lower than emissions from land use disturbances on mangroves worldwide. Our results suggest that climate effects on mangroves can become significant sources of greenhouse gases globally. [Display omitted] • The pristine mangroves in SE Brazil stock over 1851 Mg C ha−1. • Climate-relate impacts resulted in 14.6 % decrease in total ecosystem carbon stock. • The mangrove dieback lead to 40.4 % of carbon losses on the 0–30 cm soil. • Carbon dioxide emissions from the climate-relate impact was 992.8 Mg CO 2 e ha−1. • The Brazilian mangroves hold 5 % (0.52 Pg C) of the global mangrove ecosystem stock. [ABSTRACT FROM AUTHOR]

• We studied the structure of a natural and planted emerging mangroves. • The colonizing mangroves areas increased 12 and 95 times in 15 years. • Despite distinct ages, the studied mangroves present similar richness and abundance. • Local carbon sequestering is equivalent to 3% of the Brazilian industrial emissions in 2016. A planted and a natural stand that started colonizing a coastal lagoon after an artificial channel permanently connected it to the sea were studied in Brazil's Southwestern Atlantic coast to assess the ecological role of emerging mangrove forests and the ecological changes of the supporting ecosystems (i.e., coastal lagoon). In 15 years, the natural mangrove stand area increased 12 times, and the planted stand 95 times in 6 years, covering 25 and 1.9 ha, respectively. Although the natural and planted stands have different ages (approximately 42 and 6 years, respectively), their species richness and relative abundance are similar but differ in tree size. Consequently, above-ground and roots biomasses were higher in the natural stand. Compared to other mangroves from the Neotropical region, the studied mangroves' biomass and carbon stock were lower. Nevertheless, since 2003 it sequestered 4,063.1 ± 894 Mg of carbon dioxide (CO 2) from the atmosphere, only considering the forest biomass, which is equivalent to 0.03‰ of the Brazilian industrial emissions in 2016. The colonization of the lagoon by mangroves resulted in changes in the ecosystem state. This ecological change imposes an understanding of the new environment's function and dynamic to support management practices and prevent and solve conflicts among local players. [ABSTRACT FROM AUTHOR]

Mangroves are among the most relevant ecosystems in providing ecosystem services because of their capacity to act as sinks for atmospheric carbon. Thus, restoring mangroves is a strategic pathway for mitigating global climate change. Therefore, this study aimed to examine the organic matter dynamics in mangrove soils during restoration processes. Four mangrove soils under different developmental stages along the northeastern Brazilian coast were studied, including a degraded mangrove (DM); recovering mangroves after 3 years (3Y) and 7 years (7Y) of planting; and a mature mangrove (MM). The soil total organic carbon (C T ) and soil carbon stocks (SCSs) were determined for each area. Additionally, a demineralization procedure was conducted to assess the most complex humidified and recalcitrant fractions of soil organic matter and the fraction participating in organomineral interactions. The particle size distribution was also analyzed. Our results revealed significant differences in the SCS and C T values between the DM, 3Y and 7Y, and the MM, for which there was a tendency to increase in carbon content with increasing vegetative development. However, based on the metrics used to evaluate organic matter interactions with inorganic fractions, such as low rates of carbon enrichment, C recovery, and low C content after hydrofluoric acid (HF) treatment being similar for the DM and the 3Y and 7Y-this indicated that high carbon losses were coinciding with mineral dissolution. These results indicate that the organic carbon dynamics in degraded and newly planted sites depend more on organomineral interactions, both to maintain their previous SCS and increase it, than mature mangroves. Conversely, the MM appeared to have most of the soil organic carbon, as the stabilized organic matter had a complex structure with a high molecular weight and contributed less in the organomineral interactions to the SCS. These results demonstrate the role of initial mangrove vegetation development in trapping fine mineral particles and favoring organomineral interactions. These findings will help elucidate organic accumulation in different replanted mangrove restoration scenarios.

Total organic carbon (TOC) and total nitrogen (TN) concentration in the soil are an indicator of soil degradation. To understand how land-use may impact these concentrations in seasonally dry tropical forests (SDTF), we analyzed the effect of four land-uses on TOC stocks (STK.TOC) and TN stocks (STK.TN) in a semi-arid region of Brazil. Soil samples were collected in 12 trenches (three sites × four land-uses—dense caatinga (DC), open caatinga (OC), pasture (PA) and agriculture (AG)), in the 0–10; 10–20 and 20–30 cm layers or as far as the bedrock. The data were compared by the Kruskal–Wallis test (p ≤ 0.05) and similarity investigated by cluster analysis. STK.TOC and STK.TN the surface layer (0–10 cm) showed no significant difference (p ≤ 0.05) between the DC; OC and PA land-uses. The similarity in STK.TOC and STK.TN values between DC, OC and PA, indicate that it is possible to explore SDTF to produce biomass and protein by adopting open caatinga and pasture land uses on Neosols with very low TOC stocks. The greatest reduction in STK.TOC and STK.TN in the agriculture land-use may lead to soil degradation and contribute to the addition of CO2 to the atmosphere. [ABSTRACT FROM AUTHOR]